It is generally of interest to minimize power consumption in gyroscope systems to enhance their use in portable, battery-powered device applications. One method known in the art for saving power consumption is to duty-cycle a system. In a duty-cycled system, the system is initially in a low-power operating mode. Periodically, it transitions to a normal operating mode, makes a measurement and then returns to the low-power operating mode.
A difficulty in duty-cycling a gyroscope system stems from the fact that certain system state variables are very slow to respond to changes in system state. For example, the amplitude of oscillation of the gyroscope (as regulated by the AGC loop) cannot change rapidly due to the high quality factor of the MEMS oscillation. The phase-locked loop may also have relatively low bandwidth, meaning that it will be slow to respond to any disturbance affecting its VCO tuning voltage.
However, it is desirable to transition the system quickly between low-power and normal operating modes to minimize the overhead associated with mode transitions and to thereby maximize the output data rate that can be maintained while duty-cycling. The present invention addresses such a need.